Hillstream BioPharma, Inc. announced the signing of an exclusive agreement with Applied Biomedical Science Institute (ABSI) to license technology for human antibodies targeting novel HER2 and HER3 Conformational Epitopes. The goal is to develop proprietary multi-format biologics, including bi-specific antibodies, and antibody drug conjugates (ADCs). The HER2/HER3 binding ADC is targeted to have a high drug-to-antibody ratio which should increase the anti-tumoral efficacy with an enhanced bystander killing effect.

Hillstream intends to combat drug resistant cancers such as HER2-positive metastatic breast cancer, gastric cancer, lung cancer and ovarian cancer. The ErbB family of cell surface proteins, including ErbB2 or HER2 (human epidermal growth factor receptor) and Erb3 or HER3, are some of the most well-known and validated oncology drug targets. Antibodies and biologics against HER2 starting with HERCEPTIN® (trastuzumab) approved in 1998 for breast cancer, and PERJETA®, KADCYLA® and PHESGO® generated $8.4 billion in 2022 sales for Roche/Genentech.

These antibodies bind to domains II or IV of the extracellular portion of the HER2. HER2 is also one of the most validated antigens for antibody drug conjugates (ADCs) to treat HER2 positive cancers with two approved antibodies, Roche/Genentech’s KADCYLA® and Daiichi Sankyo/AstraZeneca’s ENHERTU®. The Applied Biomedical Science Institute has developed technology to target novel functional epitopes of the cancer targets HER2 and HER3.

The monoclonal antibodies being developed at ABSI are distinct from the currently approved anti-HER2 antibodies. ABSI has granted Hillstream an exclusive license agreement, and Hillstream will have the opportunity to develop HER2 and HER3 antibodies, including multi-specific, ADC, and Quatramer-based therapeutics utilizing portions of these antibodies.